Does the Cold Make Us Sick?

We are smack in the middle of winter and cold weather has taken over much of the country. Did anyone know what a polar vortex was before this year? Could anyone imagine it would have been colder in Minnesota than at the South Pole? Negative-degree temperatures in Chicago and single-digits in the south…brrr…it’s cold. Even Hell has frozen over (not that hell, the one in Michigan)!

The cold means colds and fevers and the flu, right? Do we actually get sick more often in the winter? Does the cold make us sick? Well, the answer to that may be a bit more nebulous than we think.

Don’t forget to put on your jacket and mittens! Medical folklore and old wives’ tales have forged a persistent link between the dreary, frigid weather of winter and the aches, chills, and congestion of a winter cold or flu.

Image from: Dreamstime.com

Scientists have spent countless hours and days and years trying to debunk this link and they have found that being cold or going out in the cold doesn’t actually make us sick. But, why we do get sick more often in the winter. Doctors aren’t telling us to get our flu shots in April, right? So, what gives? Does the cold have anything to do with it?

The link between icy temperatures and higher rates of infections goes back to the late 19th century when Louis Pasteur found that chickens are immune to anthrax. He speculated that their higher body temperatures (104 to 107 degrees) were responsible for this immunity. When he chilled a chicken and exposed it to anthrax, it died. Link established, and further experiments by other scientists, with rats, mice, and monkeys showed that colder animals were more susceptible to polio, pneumonia, and other diseases.

Though these animal studies proved a link for animals, no link had been shown for humans. Plenty of research has been done, but the results have been mixed at best, and it appears that cold weather does not by itself cause us to get the aches and sniffles we associate with winter. Some studies have even shown that the cold stimulates our immune systems and may actually provide more protection in winter.

No, the cold doesn’t make us sick, but it does drive us indoors and provides us with plenty of opportunity to breath recycled air and come in close contact with sick people and their infectious mucous. This is why people in sunbelt cities like Los Angeles, San Diego, and Miami get colds in winter as they still move inside when the thermometer drops to 50 degrees, but their cold seasons are not as extreme as the ones in New York, Chicago and other frigid northern cities.

Of course, like most things in science and our physical world, nothing is completely black and white. If someone gets cold enough that hypothermia sets in (the lowering of the body’s core temperature), this can suppress the immune system and increase the susceptibility to colds and flu.

Cold weather may also be indirectly responsible for colds, however, by causing the blood vessels to constrict. Vasoconstriction, the narrowing of blood vessels, especially those found in the nose, can lead to dryness. This dryness can compromise the nose’s ability to filter infections. When someone returns to the warmth, vasodilation, the opening of these blood vessels occurs. This causes your hands to get pink and your nose to start running as blood returns to it. If the runny nose is severe enough, individuals will begin mouth breathing, which bypasses the nose’s ability to filter inhaled air. Less filter, more dry air, and closer contact with infected people, means more colds and flu for everyone.

So, does the cold make us sick? It seems that the old wives’ tale that the cold will make us sick is mostly false, but also contains an element of truth. If you want to go outside and play without a jacket, or even naked, don’t worry. In fact, it’s much safer than being in a heated room with a crowd of wheezing, coughing people. Unless the cops catch you playing in the snow without your clothes – then they might throw you in a cell with wheezing, coughing criminals and their infectious mucous.